1. Technical Field
The invention relates to an electro-optical device and an electronic apparatus, and in particular, to a structure of an electro-optical device including a color filter having a plurality of coloring layers and allowing both the reflection display and transmittance display of colors to be utilized by the color filter.
2. Related Art
In general, a color filter is employed for allowing color display to be performed in a liquid crystal display (LCD) or other various electro-optical devices. This color filter is, for example, formed such that a plurality of coloring layers, such as, red, green, and blue coloring layers, are respectively disposed in every pixel and the plurality of coloring layers are arranged in a predetermined pattern. Such coloring layers are formed, for example, by a photolithography method using a photosensitive resin containing colorant (e.g., pigment, dye, or the like).
Meanwhile, there is a known display device, which has a backlight disposed at the rear side of the electro-optical device to display the visible transmission by using lights of the backlight in a relatively dark environment such as indoors or in the car, and turns off the backlight to display visible reflection by using external lights in a bright location such as outdoors. In this type of device, a transmitting region allowing lights to be transmitted and a reflecting region allowing lights to be reflected are formed within each pixel, and the transmission display is utilized by using the transmitting region and the reflection display is utilized by using the reflecting region.
In this case, the coloring layer needs to be formed at both sides of the transmitting and reflecting regions in order to utilize the color display at both sides thereof, however, lights from the backlight transmit the coloring layer in the transmitting region only once whereas external light transmit the coloring layer twice by going and returning, such that bright display is possible at the expense of color saturation in the transmission display, and it is easy to increase the color saturation at the expense of bright display in the reflection display. Accordingly, the coloring layer in the transmitting region generally needs to have higher color saturation than the coloring layer of the reflecting region.
In order to have coloring layers with different color saturations from each other in the transmitting and reflecting regions, an amount of colorants contained in the coloring layer should be changed, such that the different kinds of the coloring layers cause a manufacture process thereof to be complicated. Here, there is a well-known color filter for an LCD. The color filter has coloring layers with two colors stacked sequentially in the transmitting region among three complementary colors of cyan, magenta, and yellow while having each of the two colors disposed as a single layer in the reflecting region in order to form three primary colors of red, green, and blue colors such that a color saturation for the transmission display can be secured and a brightness of the reflection display can be obtained (e.g., refer to JP-A-2002-258029).
However, in the electro-optical device which allows both of the transmission display and the reflection display to be utilized, a substantial aperture ratio of the transmission display decreases due to the formation of the reflecting region while a substantial aperture ratio of the reflection display simultaneously decreases due to the formation of the transmitting region, such that it is difficult to secure the brightness of the display and utilize a visual balance between the two displays.
In particular, a luminance or a contrast of the reflection display is originally and significantly lower than a luminance or a contrast of the transmission display, such that the reflecting region is given priority so as to secure brightness whereas a high display quality (e.g., a contrast, color reproducibility, or the like) is required for the transmission display. Thus, it is necessary to improve the quality of the color filter in the transmitting region having a limited area in order to improve the display quality of the transmission display. However, when the coloring layers of the reflecting and transmitting regions are formed of separate materials from each other to produce high quality of the transmission display, the number of the processes of manufacturing the color filter increases, which increases the manufacture cost.